The Wnt/\u3b2-catenin pathway in human fibrotic-like diseases and its eligibility as a therapeutic target

The canonical Wnt signaling pathway is involved in a variety of biological processes like cell proliferation, cell polarity, and cell fate determination. This pathway has been extensively investigated as its deregulation is linked to different diseases, including various types of cancer, skeletal defects, birth defect disorders (including neural tube defects), metabolic diseases, neurodegenerative disorders and several fibrotic diseases like desmoid tumors. In the "on state", beta-catenin, the key effector of Wnt signaling, enters the nucleus where it binds to the members of the TCF-LEF family of transcription factors and exerts its effect on gene transcription. Disease development can be caused by direct or indirect alterations of the Wnt/\u3b2-catenin signaling. In the first case germline or somatic mutations of the Wnt components are associated to several diseases such as the familial adenomatous polyposis (FAP) - caused by germline mutations of the tumor suppressor adenomatous polyposis coli gene (APC) - and the desmoid-like fibromatosis, a sporadic tumor associated with somatic mutations of the \u3b2-catenin gene (CTNNB1). In the second case, epigenetic modifications and microenvironmental factors have been demonstrated to play a key role in Wnt pathway activation. The natural autocrine Wnt signaling acts through agonists and antagonists competing for the Wnt receptors. Anomalies in this regulation, whichever is their etiology, are an important part in the pathogenesis of Wnt pathway linked diseases. An example is promoter hypermethylation of Wnt antagonists, such as SFRPs, that causes gene silencing preventing their function and consequently leading to the activation of the Wnt pathway. Microenvironmental factors, such as the extracellular matrix, growth factors and inflammatory mediators, represent another type of indirect mechanism that influence Wnt pathway activation. A favorable microenvironment can lead to aberrant fibroblasts activation and accumulation of ECM proteins with subsequent tissue fibrosis that can evolve in fibrotic disease or tumor. Since the development and progression of several diseases is the outcome of the Wnt pathway cross-talk with other signaling pathways and inflammatory factors, it is important to consider not only direct inhibitors of the Wnt signaling pathway but also inhibitors of microenvironmental factors as promising therapeutic approaches for several tumors of fibrotic origin

Growth rate and myofibroblast differentiation of desmoid fibroblast-like cells are modulated by TGF-\u3b2 signaling

Abstract Desmoid-like fibromatosis (DF) is a rare myofibroblastic benign tumor, often associated with local and repeated injuries, spontaneous regression and stabilization of disease progression suggesting the involvement of altered Wnt/-catenin signaling activation and/or aberrant response of the DF cells to external environmental stimuli. The aim of this study was to investigate the response of DF cells to microenvironmental factors such as inflammatory and growth factors or hormones. We observed that the inflammatory cytokine, transforming growth factor- (TGF-1) stimulated cell growth and myofibroblast differentiation of DF cells regardless of the presence of a -catenin mutation. The role of TGF-1 in cell growth and myogenic differentiation of in vitro cultures of primary DF cells and normal fibroblasts was investigated by gene and protein expression analyses. We demonstrated that TGF-1 exerted its role via the canonical Smad pathway with the phosphorylation of Smad3 being crucial for TGF-1 dependent DF cell growth and myofibroblastic differentiation. Furthermore we demonstrated that cell confluence is a critical determinant of TGF-1 inducing the DF myofibroblast differentiation, implying that the intercellular communications have an important role on the DF myofibroblast behavior. We observed the formation of an increased stress-fiber pattern in DF cells with increased projected cell area and stronger cell-cell contacts in presence of TGF-1. These results demonstrated that TGF-1 plays a crucial role in the DF cells growth and, together with cell-cell interactions, in DF myofibroblast conversion; we also highlighted that the cellular sensitivity to this cytokine was an intrinsic feature of the DF cells

Two Novel Homozygous SACS Mutations in Unrelated Patients Including the First Reported Case of Paternal UPD as an Etiologic Cause of ARSACS.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay, more commonly known as ARSACS, is an early-onset cerebellar ataxia with spasticity, amyotrophy, nystagmus, dysarthria, and peripheral neuropathy. SACS is the only gene known to be associated with the ARSACS phenotype. To date, 55 mutations have been reported; of these, only five in Italian patients. We found two novel homozygous nonsense mutations in the giant exon of SACS gene in two unrelated patients with classical ARSACS phenotype. Characterization of the homozygous nature of the mutations through genotyping of the parents, quantitative DNA analysis and indirect STS studies permitted us to confirm in one of the cases that uniparental isodisomy of the paternal chromosome 13 carrying the mutated SACS gene played an etiologic role in the disease. © Springer Science+Business Media, LLC 2010.SCOPUS: ar.jinfo:eu-repo/semantics/publishe